Chapter 35 Plant Structure Flashcards
What is developmental plasticity?
the ability to alter itself in response to its environment
What plant exhibits development plasticity?
fanwort
Where is developmental plasticity most marked?
in plants rather than animals
What is morphology?
form
Describe the hierarchy of organs
plants have organs composed of different tissues, which in turn are composed of cells.
What are the three basic organs of plants?
roots, stems, and leaves
What are the two organ systems of plants?
root system and a shoot system
How do roots and shoots rely on each other?
Roots rely on sugar produced by photosynthesis in the shoot system.
Shoots rely on water and minerals absorbed by the root system.
What is vegetative growth?
production of nonreproductive leaves stems and roots and reproductive growth
What are the functions of root?
- Anchoring the plant
- Absorbing minerals and water
- Storing organic nutrients
What is a taproot system?
one main vertical root (taproot) that gives rise to some large lateral roots, or branch roots
What are adventitious roots?
Adventitious roots arise from stems or leaves
What is a fibrous root system?
many thin lateral roots with no main root
What plants have a fibrous root system?
seedless vascular plants and monocots
Where does absorption of water and minerals occur?
near root hairs
What is the function of root hairs?
they increase the surface area and function in absorption
What are four examples of modified roots?
Prop roots (corn), storage roots (beets), pneumatophores (mangroves), buttress roots (support)
What are stems?
organs consisting of nodes and internodes
What are nodes?
the points at which leaves are attached
What are internodes?
the stem segments between nodes
What is an axillary bud?
a structure that has the potential to form a lateral shoot, or branch
What is an apical bud?
Apical bud, or terminal bud, is located near the shoot tip and causes elongation of a young shoot
What is apical dominance?
helps to maintain dormancy in most nonapical buds
What are modified stems often mistaken for?
roots
List four types of modified stems.
rhizomes, bulbs, stolons, tubers
What are rhizomes?
Rhizomes- horizontal shoot that grows just below the surface
What are bulbs?
Bulbs- layered vertical underground shoots
What are stolons?
Stolons- horizontal shoots that grow along the surface
What are tubers?
Tubers- enlarged ends of rhizomes or stolons specialized for storing food
What are the components of leaves?
Leaves generally consist of a flattened blade and a stalk called the petiole, which joins the leaf to a node of the stem
What do monocots lack in leaf structure?
Monocots lack petioles, instead the base of the leaf forms a sheath that envelopes the stem
Describe a simple leaf.
single undivided blade
Describe a compound leaf.
blades that consists of multiple leaflets
Describe a doubly compound leaf.
leaflets divided into smaller leaflets
List five types of modified leaves.
tendrils, spines, storage leaves, reproductive leaves, bracts
What are tendrils?
Modified leaves, clings
What are spines?
modified leaves, prickly, photosynthesis is carried out mainly by the fleshy stems
What are storage leaves?
modified leaves, succulent plant leaves store water
What are reproductive leaves?
modified leaves, little plantlets fall off and take root in the soil
What are bracts?
modified leaves, look like petals, attract pollinators
What are the three types of tissue?
dermal, vascular, ground
What is the dermal tissue system?
the plants outer protective covering
What is the dermal tissue system is nonwoody plants?
epidermis
What is the cuticle?
A waxy coating called the cuticle helps prevent water loss from the epidermis.
What is the dermal tissue system in woody plants?
protective tissues called periderm replace the epidermis in older regions of stems and roots
What are trichomes?
Trichomes are outgrowths of the shoot epidermis and can help with insect defense, reduce water loss and reflect excess light
What is the function of the vascular tissue system?
carries out long-distance transport of materials between roots and shoots
What is te function of the xylem?
conveys water and dissolved minerals upward from roots into the shoots
What is the function of the phloem?
transports organic nutrients from where they are made to where they are needed
What is the vascular system collectively called?
the stele
What is the ground tissue system made up of?
tissues that are neither dermal nor vascular
What is contained in ground tissue?
plastids for storage
What is pith?
ground tissue internal to the vascular tissue
What is cortex?
ground tissue external to the vascular tissue
What are three functions of ground tissue?
storage, photosynthesis, and support
What are the 5 major types of plant cells?
parenchyma, collenchyma, sclerenchyma, xylem, phloem
What type of tissues are parenchyma, collenchyma, and sclerenchyma?
ground
What type of tissues are xylem and phloem?
vascular
Describe parenchyma cells.
- Photosynthesis, storage.
- Large central vacuole
- Able to transform into different types of cells
- Thin flexible cell walls:
Describe collenchyma cells.
thicker cell walls for flexible support
Describe sclerenchyma cells.
- thick secondary cell walls reinforced with lignin for rigid, sturdy support
- dead at functional maturity
Describe two types of sclerenchyma cells.
- Sclereids are short and irregular in shape and have thick lignified secondary walls.
- Fibers are long and slender and arranged in threads.
What are the two types of xylem cells?
tracheids , vessel elements
Where are tracheids found?
found in the xylem of all vascular plants
Where are vessel elements found?
common to most angiosperms and a few gymnosperms
Describe tracheids.
- Long thin cells with tapered ends
- Their walls are often interrupted by pits, thinner regions where only primary walls are present.
- Water can migrate laterally through cells.
Describe vessel elements.
- Wider, shorter, thinner walled, and less tapered cells
- Vessel elements align end to end to form long micropipes called vessels.
- End walls have perforation plates that enable water to flow freely
What are phloem cells called?
sieve tube elements
Describe sieve tube elements.
-alive at functional maturity, though they lack organelles
Describe components associated with sieve-tube elements.
- Sieve plates are the porous end walls that allow fluid to flow between cells along the sieve tube.
- Each sieve-tube element has a companion cell whose nucleus and ribosomes serve both cells.
What is the function of meristems?
generate cells for new organs
What is indeterminate growth?
a plant growing throughout its life
What is determinate growth?
plant organs cease to grow at a certain size
What are annuals?
plants that complete their life cycle in a year or less
What are biennials?
plants that require two growing seasons (radishes and carrots)
What are perennials?
plants that live for many years
How do perennials die?
infection or severe environmental trauma
What are meristems?
are growth regions - have perpetual embryonic tissue that allows for indeterminate growth
What are apical meristems?
located at the tips of roots and shoots and at the axillary buds of shoots
What do apical meristems perform?
located at the tips of roots and shoots and at the axillary buds of shoots
What do lateral meristems do?
add thickness to woody plants, a process called secondary growth
What are the two lateral meristems?
the vascular cambium and the cork cambium
What does the vascular cambium do?
adds layers of vascular tissue called secondary xylem = wood and secondary phloem
What does the cork cambium do?
replaces the epidermis with periderm, which is thicker and tougher
What are initials?
Initials are cells that remain as sources of new cells
What are derivatives?
Derivatives cells displaced from the meristem until the cells they produce become specialized within developing tissues
What do bud scales do?
protect a dormant apical bud
Where are bud scars?
Bud scars are left behind where the bud scales have fallen
Where are leaf scars?
Leaf scars are left behind where leaves have fallen
What does the root cap do?
- protects the apical meristem as the root pushes through soil
- Root cap secretes polysaccharide slime that lubricates the soil around the tip of the root
What are the three zones of growth?
zone of cell division, zone of elongation, zone of maturation
What is the zone of cell division?
root apical meristem and root cap, new root cells are produced in this region
What is the zone of elongation?
where root cells elongate up to 10x their original length
What is the zone of maturation/differentiation?
where root cells complete their differentiation and become distinct cell types
What does the primary growth of roots produce?
epidermis, ground tissue, and vascular tissue
What is the stele in most roots?
a vascular cylinder
Where is the cortex located?
the region between the vascular cylinder and epidermis
What is the innermost layer of the cortex called?
the endodermis
What cells fill the cortex?
parenchyma cells
Where do lateral roots arise?
from within the pericycle
What is the pericycle?
the outermost cell layer in the vascular cylinder
What do leaves develop from?
leaf primordia, fingerlike projections along the sides of the apical meristem
What do axillary bud develop from?
meristematic cells left at the bases of leaf primordia
What do lateral shoots develop from?
from axillary buds on the stem’s surface
What are intercalary meristems?
areas of meristematic tissue separated from the apical meristem
What do intercalary meristems allow for?
Allows grasses to regrow after cutting
How is the vascular tissue arranged in monocots?
In most monocot stems, the vascular bundles are scattered throughout the ground tissue, rather than forming a ring.
How is the vascular tissue arranged in eudicots?
In most eudicots, the vascular tissue consists of vascular bundles that are arranged in a ring.
What perforated the epidermis of leaves?
stomata, which allow CO2 exchange between the air and the photosynthetic cells in a leaf
What are stomata guarded by?
Each stomatal pore is flanked by two guard cells, which regulate its opening and closing
What is the group tissue in the leaf called?
mesophyll, is sandwiched between the upper and lower epidermis.
What are the types of mesophyll in a leaf?
Below the palisade mesophyll in the upper part of the leaf is loosely arranged spongy mesophyll, where gas exchange occurs.
What are leaf traces?
Leaf traces, connections from vascular bundles in the stem pass through petioles and into leaves
What are veins and what do they function as?
Veins are the leaf’s vascular bundles and function as the leaf’s skeleton
What are veins enclosed by?
Each vein in a leaf is enclosed by a protective bundle sheath
What is the function of secondary growth?
adds girth to stems and roots in woody plants
What does the secondary plant body consist of?
The secondary plant body consists of tissues produced by the vascular cambium and cork cambium
What does the vascular cambium develop from?
undifferentiated parenchyma cells
What does the vascular cambium appear as?
- In cross section, the vascular cambium appears as a ring of initials.
- The initials increase the vascular cambium’s circumference and add secondary xylem to the inside and secondary phloem to the outside.
What is the vascular cambium?
a cylinder of meristematic cells one cell layer thick
What does the vascular cambium do?
adds secondary xylem (wood) and secondary phloem increasing vascular flow and support for the shoot system
What does the cork cambium do?
The cork cambium produces a tough thick covering of mainly wax-impregnated cells that protect the stem from water loss and invasion by insects, bacteria, and fungi
Where are tree rings visible?
Tree rings are visible where late and early wood meet, and can be used to estimate a tree’s age.
What is dendrochronology?
is the analysis of tree ring growth patterns, and can be used to study past climate change.
What is the the heartwood and how does it change as the tree ages?
As a tree or woody shrub ages, the older layers of secondary xylem, the heartwood, no longer transport water and minerals.
What is the sapwood and what does it do?
The outer layers, known as sapwood, still transport materials through the xylem.
What occurs to phloem over time?
Older secondary phloem sloughs off and does not accumulate.
What is bark made up of?
Bark is made up of secondary phloem and layers of periderm
What does periderm consist of?
the cork cambium plus the layers of cork cells it produces
What is bark?
Bark consists of all the tissues external to the vascular cambium, including secondary phloem and periderm
What are lenticels?
Lenticels in the periderm allow for gas exchange between living stem or root cells and the outside air
What is morphogenesis?
the development of body form and organization
How do plants grow rapidly and cheaply?
Plant cells grow rapidly and “cheaply” by intake and storage of water in vacuoles
Where do plant cells primarily expand?
Plant cells expand primarily along the plant’s main axis
What do cellulose microfibrils do?
Cellulose microfibrils in the cell wall restrict the direction of cell elongation
What is pattern formation?
the development of specific structures in specific locations
What occurs in cellular differentiation?
In cellular differentiation, cells of a developing organism synthesize different proteins and diverge in structure and function even though they have a common genome.
What does cellular differentiation depend on?
Cellular differentiation to a large extent depends on positional information and is affected by homeotic genes.
What determines what type of cell a cell will become?
its final position
What does flower formation involve?
Flower formation involves a phase change from vegetative growth to reproductive growth.
What must be switched on for flowering?
Transition from vegetative growth to flowering is associated with the switching on of floral meristem identity genes.
What is the ABC model of flower formation?
c
